The preparation of alkyl-substituted 1,1,1-trialkylethanes, such as neopentane, by hydrogenation of a corresponding tertiary alkylcarbinol has been proposed by Ford et al. (U.S. Pat. No. 2,440,678). A cobalt hydrogenation catalyst was used, at temperatures of 100.degree.-400.degree. C. and pressures above 7 Kg/cm.sup.2. However, a preference was recited for pressures above 70 Kg/cm.sup.2 and temperatures of 175.degree.-375.degree. C.
Prior routes to neopentane include synthesis for a tert-butyl halide and dimethyl zinc, as recited by Whitmore et al., J. Am. Chem. Soc., vol 55 (1933), page 3803: EQU 2(CH.sub.3).sub.3 CCl+Zn(CH.sub.3).sub.2 .fwdarw.ZnCl.sub.2 +2(CH.sub.3).sub.4 C
An alternative route to neopentane, in accordance with Whitmore et al., J. Am. Chem. Soc., vol. 61 (1939), page 1586, is by reaction between neopentyl iodide and potassium hydroxide: ##STR1##
It was further shown by Whitmore et al., J. Am. Chem. Soc., vol 63 (1941), page 124, that reaction between neopentyl chloride and sodium produced neopentane, as well as 1,1-dimethylcyclopropane: ##STR2##
Duckwall, Jr., in U.S. Pat. No. 4,405,819, has proposed obtaining alcohols from acids, which can be branched, using a metal-containing hydrogenation catalyst. However, the process requires a sweep gas, containing carbon monoxide, and does not appear to contemplate the further reduction of alcohol to alkane.
Wall has recited, in U.S. Pat. No. 4,149,021, the hydrogenation of esters, apparently of linear acids, using a cobalt/zinc/copper catalyst. The use of a copper/zinc oxide catalyst is said to be undesirable, because of catalyst instability.
Wilkes has disclosed, in U.S. Pat. No. 4,283,581, a process for hydrogenating feed stocks, such as glycolide and glycolates, to ethylene glycol, using a copper/zinc oxide catalyst, supported on silica. The reference indicates that, using a similar copper/zinc oxide/alumina catalyst, low conversions are obtained at about 190.degree. C. and a pressure of 105 Kg/cm.sup.2. Higher conversion (46%) was reported at a higher temperature.
The reduction of branched esters, e.g., pivalic acid esters, to alcohols, has been disclosed by Kurhajec in U.S. Pat. No. 2,986,577. A copper chromite catalyst was employed. The reaction required a high hydrogen pressure, of the order of 232 Kg/cm.sup.2.
Pine et al. (U.S. Pat. No. 3,361,832) have accomplished conversion of branched acids, generally in the form of esters, to alcohols employing a molybdenum sulfide catalyst, under relatively low temperatures and pressures. However, for high selectivity toward corresponding alcohols, e.g., neoheptanol, the use of high pressures, well above about 70 Kg/cm.sup.2, are required.
Neopentane is reported as being a minor product (0.4%) of the hydrogenation of methyl pivalate, using a molybdenum sulfide catalyst, Landa et al., Chem. Listy, vol. 51 (1957), 452-458. The major product (74.0%) was 2-methylbutane. Under the same conditions, 71% of neopentanol was converted to 24% of neopentane and 30% of isopentane.
Landa et al. have also reported hydrogenation of less highly branched alcohols to hydrocarbons, Chem. Listy, vol. 50 (1956), 569-572.
Reduction of alpha,alpha-dimethylalkanoic acids over copper chromite catalyst has been recited by Puzitskii et al., Neftekhimiya, vol. 7 (2) (1967), 280-285. Reduction of methyl pivalate to neopentyl alcohol over copper chromite has been reported by Shutikova et al., Tr. Vses. Nauch.-Issled. Inst. Natur. Dushist. Veshchestv, no. 7 (1965), 16-20.
The use of Adkins' copper-chromium oxide catalyst, J. Am. Chem. Soc., vol. 72 (1950), 2626-2629, was recited as a route to neopentanol from methyl pivalate, Landa et al., Chem. Listy, vol. 51 (1957), 452-458.
Catalytic reduction of acids, having branched structures, other than of the alpha, alpha, alpha-trisubstituted type, are disclosed by:
U.S. Pat. No. 2,607,807: Ford et al. PA1 U.S. Pat. No. 3,478,112: Adam et al. PA1 U.S. Pat. No. 3,920,766: Jubin, Jr. et al. PA1 U.S. Pat. No. 4,433,175: Kaufhold PA1 U.S. Pat. No. 1,839,974: Lazier PA1 U.S. Pat. No. 2,091,800: Adkins et al. PA1 U.S. Pat. No. 2,110,483: Guyer et al. PA1 U.S. Pat. No. 2,275,152: Lazier PA1 U.S. Pat. No. 2,340,688: Richardson et al. PA1 U.S. Pat. No. 3,985,814: Dougherty PA1 U.S. Pat. No. 4,104,478: Trivedi PA1 U.S. Pat. No. 4,398,039: Pesa et al. PA1 U.S. Pat. No. 4,443,639: Pesa et al. PA1 Japan Pat. No. 57032237-A: Sumitomo Chemical K.K. PA1 German OLS No. 2,613,226: Demmering (Sept. 9, 1977) PA1 WO 82/03854: Davy McKee PA1 Soviet Union Pat. No. 899113: Sultanov et al.
Hydrogenation of linear acids or their esters to corresponding alcohols has been disclosed in:
Vedage et al., J. Catalysis, vol. 77 (1982), page 558.
Of the foregoing, the Vedage et al. article discloses employing a copper/zinc oxide catalyst, normally used for methanol synthesis, to hydrogenate propanoic acid to propanol. The Davy McKee patent is of similar interest with respect to reduction of butyl butyrate or other esters. The reference contemplates reduction of branched esters, e.g. isobutyrates.
Demethylation of hydrocarbons, under hydrogenation conditions, has been disclosed by Haensel et al., U.S. Pat. Nos. 2,422,670; 2,422,674 and 2,422,675 and J. Am. Chem. Soc., vol. 68 (1946), page 345.
It is accordingly apparent that direct synthesis of highly branched hydrocarbons, particularly of the neoalkane type, from either neoacids or neoalcohols, is a synthetic route which has not heretofore been utilized successfully.